Process for treating citrus wastes to obtain water insoluble essential oils

ABSTRACT

Citrus fruit peels and pulp are treated by coking in the aqueous phase in the absence of air or oxygen followed by heating of the resulting coke to give water insoluble essential oils such as orange oils. A carrier gas such as nitrogen preferably is used to entrain the hydrocarbons evolved by heating the coke.

Cole et al.

[ 'Aug. 12, 1975 PROCESS FOR TREATING CITRUS WASTES TO OBTAIN WATER INSOLUBLE [56] References Cited ESSENTIAL OILS UNlTED STATES PATENTS Inventors: Edward L. Cole, Fishkill; Howard V. 2,601,635 6/1952 Romagnan 260/236.6 Hess, Glenham, both of N,Y 2,708,627 5/l955 Toulmin 260/236.6 2,975,170 3/1961 Herrick et a1 260/236.6

Assigneez Texaco Inc., New York, NY. r y g Filed: Nov. 24, 1972 Primary Examiner-Norman Yudkoff Assistant Examiner-David Edwards Appl 309391 Attorney, Agent, or FirmT. H. Whaley; C. G. Ries Related US. Application Data Continuation-impart of Ser. No. 887,684, Dec. 23, 1969, abandoned, which is a continuation-in-part of Ser. No. 780,080, Nov. 29, 1968, Pat. No. 3,507,788.

[5 7 ABSTRACT Citrus fruit peels and pulp are treated by coking in the aqueous phase. in the absence of air or oxygen followed by heating of the resulting coke to give water 201/2'5; 269/236'6; 201/259; insoluble essential oils such as orange oils. A carrier 1 t Cl 201/45 20 1 $1 6523; 30 gas such as nitrogen preferably is used to entrain the h d b l d b h t th k Field of Search 260/2366; 201/25, 25, y mar Ons evo y ea mg e co e 201/45, 33; 2l()/7l; 203/49 4 Claims, 1 Drawing Figure PATENTED AUG 1 ZIQYS PROCESS FOR TREATING CITRUS WASTES TO OBTAIN WATER INSOLUBLE ESSENTIAL OILS CROSS REFERENCE TO COPENDING APPLICATION This application is a continuation-in-part of commonly assigned application Ser. No. 887,684 filed Dec. 23, 1969, and now abandoned itself a continuation-inpart of application Ser. No. 780,080, filed Nov. 29, I968 and now US. Pat. No. 3,507,788.

BACKGROUND OF THE INVENTION The essential oils industry has for many years resorted to substantially the same processes for extracting citrus oils from citrus fruits. It has made little use of peels and pulp except for the obtaining of low grade oils.

Generally, the peel after expression of the oil still contains essential oils retained by the albedo. These oils can be recovered by steam distillation of the waste peel but are of mediocre quality. typical of distilled citrus oils.

The peels and pulp can also be soaked in hot lime so lution to gelatinize the pectins. The resulting mass is then submitted to high pressure to express a watery liquid containing oil which is concentrated for the production of molasses During concentration distilled oil called stripper oil can be recovered but this oil is very harsh and can only be used in non-flavoring applications such as in insect sprays; etc.

SUMMARY OF THE INVENTION In accordance with the claimed invention it has been discovered that when citrus fruit wastes, including peels and pulp, are coked in the liquid phase in the absence of air or oxygen and the coke so formed is heated. it will liberate an oil fraction consisting essentially of essential oils in an appreciable yield.

DETAILED DESCRIPTION OF THE INVENTION In accordance with the claimed invention, citrus wastes including peels and pulps of oranges, tangerines, lemons, grapefruits are coked at a temperature ranging from 350 to 750F. and preferably between about 385 and 550F. in the liquid phase in the absence of air or oxygen under autogeneous pressure of about 300 to 1000 p.s.i.g. for a coking time ranging from about ().I minute to 2 hours and preferably from 1 minute to minutes under turbulent flow conditions characterized by a Reynolds number which is in excess of 2,000 and preferably in excess of 4,000. The Reynolds number is defined as:

where:

N, Reynolds Number I) Inside Diameter of tube. ft.

1- Average linear velocity. ft/sec c Fluid viscosity, lb/cu. ft.

1. Fluid viscosity, lb/ft. (sec) While not wishing to be bound by any particular theory it is believed that under the operation condition of the present process the molecules of essential oil constituents coke more slowly than the molecules of other citrus waste constituent and become occluded in the coke formed by the latter.

BRIEF DESCRIPTION OF THE DRAWING The invention can best be described by reference to the single FIGURE of the accompanying drawing, which shows apparatus for treating citrus wastes to obtain citrus oils.

DESCRIPTION OF SPECIFIC EMBODIMENTS In the apparatus shown in the figure, citrus fruit peels and pulp are fed into a hopper l0 communicating with a masticator consisting essentially of a gear pump with a cutter head. The broken up waste then passes to piston pump 7 which pumps it through heat exchanger 16 and then to heater 8 which has a coker tube from which air and oxygen are excluded by vacuum, by flushing with an inert gas such as nitrogen or by other means. The coked slurry is in heat exchange relationship with the feed by pump 7 and then passes on to a filter 20 where the coke is separated from the major portion of the water. At this point it should be noted that for the purpose of the invention a filter may be replaced here with a centrifuge or by a cyclone separator. The filter coke which results from the separation procedure is fed through line 24 to kiln 26 while the waste water passes through line 22 for subsequent use as washwaters and the like. In kiln 26 the wet cake is contacted with steam in order to distill overhead the monoterpene hydrocarbons and the water. The overhead is condensed in condenser 28 to separate the gas phase (line 35), citrus oil (through line 37) and the water phase (through line 39) in separator 30. A substantially dry coke is taken off the bottom of the kiln and may be used as a fuel to heat reactor I8 and/or processed to produce activated carbon or used as cattle feed. The gas stream taken off the separator through line 35 is useful as a source of high purity carbon dioxide for dry ice manufacture and the like. The effluent water taken off through lines 22 and 39 can be reused but they will have a substantial Biological Oxygen Demand which can be reduced, if desired, by air oxidation or biological treatment. The invention is further illustrated by the following examples.

EXAMPLE I In an example of the practice of the invention, 1 grams of orange peels and 440 grams of distilled water were slurried in a Waring Blender. The blend was placed in a 1960 ml. rocking autoclave. The autoclave was evacuated to about 5 lb. p.s.i.g. and heated to 4l()F. The autoclave was held at this temperature for 2 hours, cooled and 4760 ml. of gas. recovered.

The coke material in the autoclave was poured out and 200 ml. of water used to wash out the autoclave.

Charged I538 grams of coke slurry to vacuum filter. Recovered 1025 grams of liquid, pH-S and 5l2 grams of wet solids. The wet solids were placed in a round bottom flask fitted with a heating mantle and a water condenser. The flask was heated and a slow stream of nitrogen was introduced that acted as a carrier gas. The flask was heated to about 400F. and 338 grams of liquid were recovered. The liquid was placed in a separatory funnel and 12 grams of an upper oily layer. idcnti fied as orange oil. was recovered. I65 grams of damp coke was recovered from the flask. The coke was dried on a steam plate and amounted to 108 grams. The tests are shown as follows in Table I.

Table 1 Sample Orange Oil Dry oke Gas Yield. Wt.'/( Basis L09 9.8 0.845 Peels Sample No. L-68 Nitrogen. Wtf/z Sulfur. Wt.71

Ash. Wt.'/( Carbon. Wtf/r Hydrogen, Wt.'7( Bromine No.

Infrared Spectrum l 28.3 ldentificd as limonene Odor Orange Mole 660 grams of orange peels and pulp slurried with 440 grams of water in a Waring Blender. 100 grams of the slurry was removed and tested as follows:

Solids. wtf/l 10.8 Ash. wt.'/r 0.038 COD. mg. Og/L 100.000 pH 4 The remaining slurry was placed in a l960 ml. autoclave. The autoclave was flushed with nitrogen. sealed. and heat applied as follows:

Time Temp. F. Pressure. psig 10 AM 80 0 l I do. 272 l2 NOON 408 300 l PM 4l0 300 2 do. 404 275 The heat was shut-off and the autoclave cooled to room temperature, 82F. The prcssure was psig. The autoclave was depressured and a total of 2260 ml. of gas was collected. 971 grams of material was removed from the autoclave. The product was filtered. Recovered 778 grams of filtrate and 175 grams of filter cake (coke). The coke had the odor of limonene.

EXAMPLE in 261 grams of orange peel and pulp slurried with 600 grams of water in a Waring Blender. The slurry was placed in a 1960 ml. autoclave. The autoclave was flushed with nitrogen and sealed. The temperature was 84F. and the gage reading (psig) was zero. The autoclave was heated to 550F. and held at this temperature for 2 hours. The temperature-pressure relations at the treating conditions are as follows:

Elapsc Temp. Pressure Time. Hrs. F. psig 0 55X l 100 1 552 1 I00 2 554 1 I00 The heatwas shut-off and thc autoclave cooled to 82F. The pressure on "the autoclave was l25 psig. Vented autoclave. Recovered 799 grams of liquid and coke from the autoclave. A trace of clear oil was noted that had the odor of limonene. The coke was separated from the oil by filtration. Recovered 50 grams wet coke and 749 grams filtrate. The coke was dried on a steam plate, recovered 35.0 grams. The following tests were carried out: 5

26] grams orange peel and pulp slurried with 600 grams of water in'a Waring Blender. The slurry was placed in a 1960 ml. autoclave. The autoclave was flushed with .nitrogen'and sealed. The temperature was 88F. and the gage reading (p.s.i.g.) was zero. The autcclavc was heated to 450F. and held at this temperature for 2-hours. The 'temperaturepressure relations at the treating conditions are as follows:

Elapse Temp. Pressure Time. Hours F. psig The autoclave was then cooled to 90F, the pressure was p.s.i.g. Vented gas from autoclave. A 541 gram portion of the liquid-coke product was then filtrated. lt was noted that a trace of orange oil floated on the liquid-coke from autoclave. Filtered. recovered 410 grams filtrate and 57 grams of wet coke. The coke when dried on steamplate weighed l8 grams. During drying of coke a strong odor of limonene was noted.

Orange Sample Change Filtrate Oil Gas COD. mg O. ./l. Ash. 1. '4 Carbon. Wt Hydrogen. Wtfii Sulfur. Wtfi? Nitrogen. Wtfii Phosphorous. WU/I Potassium. Wt.// ()dor Mule '71 H.

"ZOO

-Continued Dry Orange Sample Change Filtrate Coke Oil Gas While nitrogen has been used in the above examples it will be appreciated that other inert gases are equivalent thereto for the purposes of the invention. Similarly,

it will be appreciated that the process of the inventiontial oils comprising coking said citrus wastes in the aqueous phase under autogeneous pressure at a temperature of about 350 to 750F. in the absence of air or oxygen for a coking time ranging from about 0.1 minute to about 2 hours under turbulent flow conditions characterized by a Reynolds number in excess of 2000, to form coke mixed with essential oils separating the coke so formed from the aqueous phase and heating said coke to distill off said essential oils.

2. Process according to claim 1 wherein an inert carrier gas is used during said heating of said coke to entrain said oils therewith.

3. Process according to claim 2 wherein said gas is nitrogen.

4. Process according to claim 1 wherein said coke is heated to about 400F. to distill off said hydrocarbons. 

1. PROCESS FOR TREATING CITRUS WASTES TO OBTAIN ESSENTIAL OILS COMPRISING COKING SAID CITRUS WASTES IN THE AQUEOUS PHASE UNDER AUTOGENEOUS PRESSURE AT A TEMPERATURE OF ABOUT 350* TO 750*F. IN THE ABSENCE OF AIR OF OXYGEN FOR A COKING TIME RANGEING FROM ABOUT 0.1 MINUTE TO ABOUT 2 HOURS UNDER TURBULENT FLOW CONDITIONS CHARACTERIZED BY A REYNOLDS NUMBER IN EXCESS OF 2000, TO FORM COKE MIXED WITH ESSENTIAL OILS SEPARATING THE COKE SO FORMED FROM THE AQUEOUS PHASE AND HEATING SAID COKE TO DISTILL OF SAID ESSENTIAL OILS.
 2. Process according to claim 1 wherein an inert carrier gas is used during said heating of said coke to entrain said oils therewith.
 3. Process according to claim 2 wherein said gas is nitrogen.
 4. Process according to claim 1 wherein said coke is heated to about 400*F. to distill off said hydrocarbons. 